This invention relates in general to polyimide coatings and adhesives and more specifically to methods and compositions for producing imide precursors and polyimides for use as adhesives and coatings.
A number of different imide-based coating and adhesive compositions have been described in prior patents, such as those described in U.S. Pat. Nos. 4,161,477; 4,183,838 and 4,183,139. These prior polyimide forming compositions and methods produced polyimide coatings and adhesives suitable for some applications but a number of problems remained limiting the usefulness of such polyimides. These problems have been overcome by our methods and compositions and the coatings and adhesives we produce.
Prior coating compositions often did not adhere well to both metallic and non-metallic surfaces especially when fillers were used, and the adhesive compositions often had low peel strength, especially at elevated temperatures. The prior materials required high reaction temperatures and/or long periods at elevated temperatures to produce imide precursors and special vessels or reactors to produce said precursors which are very costly and processes time consuming.
Thus, it can be seen that there is a continuing need for polyimide materials having improved production methods and compositions.
It is therefore an object of this invention to provide methods and compositions for the production of imide precursors and polyimide coatings and adhesives which overcome the above-noted problems.
Another object of this invention is to provide a method of producing imide precursors which uses relatively low temperatures and short heating periods.
A further object of this invention is to produce polyimide coatings and adhesives having superior physical properties including freedom from pinholes, bubbles and similar defects, high peel resistance and resistance to abrasion and high temperatures.
Yet another object of this invention is to provide polyimide forming precursor compositions which have improved shelf lives, adhere well to a variety of metallic and non-metallic substrates and to shape edges, and can be applied using a variety of solvents and conventional coating techniques.